Percentage calculator



Dec. 17, 1963 R. A. coLLlscHoNN PERCENTAGE CALCULATOR Filed oet. 9, 1961 NN\ SW] INV EN TOR.

United States Patent() 3,114,504 PERCENTAGE CALCULATOR Robert A. Collischonn, R.F.D. 2, Longridge Road, Danbury, Conn. Filed Oct. 9, 1961, Ser. No. 143,855 1 Claim. (Cl. 23S-69) This invention relates to apparatus for rapid multiplicaton and, more particularly, to an improved-slide rule device for accomplishing such calculations.

Many persons iind it necessary in their daily employment to constantly calculate particular percentages of various amounts. In states having sales taxes, for example, persons selling to the public will usually be required to make such calculations. Many prior art devices have been employed to accomplish the necessary calculations. However, nearly all such devices are of the calculating machine type and are thus quite expensive and complicated.

It is, therefore, the primary object of this invention to develop a simplified device for multiplication.

Another object is to develop such a device adapted to provide the various products of a given number.

Another object is to provide such a device especially adapted for the calculations of percentage sales taxes.

These objects are achieved by providing an apparatus comprising a body member having thereon a first line of decimal indicia. A plurality of sliders are individually slidable parallel to the first line of indicia. Each slider carries a product line of equally spaced indicia representing the product of (l) the fixed decimal number, (2) each of the decimal indicia of the first line, and (3) a power of ten. The power of ten is different for each slider. Means are also provided for aligning each of the sliders relative to the first line of indicia.

It is to be understood that the term decimaL as used herein, refers to a numbering system to the base ten as differentiated from a system, such as the binary, using a different base.

A more complete understanding of this invention may be had by reference to the following description, the appended claim, and the figures of the attached drawing wherein:

FIG. 1 is a plan view of a device constructed in accordance with the invention;

FIG. 2 is a cross-section taken along the line 2 2 of FIG. 1;

FIG. 3 is a cross-section taken along the line 3 3 of FIG. 1;

FIG. 4 is a plan view of another' embodiment of this invention; and

FIG. 5 is a cross-section taken along line 5 5 of FIG. 4.

As will be seen by reference to FIG. 1, a body member is provided with a plurality of longitudinal grooves 12 which extend substantially its entire length. The tops of grooves 12 are open on the left end of the device as shown in FIG. l, but are closed on the right end with the exception of a viewing window 14 which may be glass covered as shown.

Within grooves 12 there are positioned sliders 16, 18, 20, 22. Each slider is approximately half the length of its groove 12. At the left end of each slider there is a suitable tab 24 for providing movement. A line of numbers from zero to nine is printed along the face of member 10 so that the tab 24 of each of the sliders may be positioned in line with any of the numbers.

Each of the sliders is designed to present the product of (l) a fixed number, (2) a selected digit, and (3) a power of ten. Consequently, the left end of body 10 carries notations which indicate the power of ten multiplied by that particular slide. Thus, in FIG. l, alongside slide Fn 1C@ 16 there is the symbol O00 to represent thousands; alongside slide 18 the symbol 00 to represent hundreds; alongside slide 20 the symbol 0 to represent tens; and alongside slide 22 the symbol l to represent units Additionally, each slider carries upon its surface the various products of the fixed number, the various digits, and its own power of ten. The device selected for illustration is adapted for use in calculating sales taxes in a state having a 3.5% rate. The slider 16, therefore, carries the various sums of (3.5%) (1000) (x) where x is any number from zero to nine.

The operation of the device will be more apparent from the following example and FIG. l. Assume it is desired to calculate the sales tax at a rate of 3.5% on a sale of $5,342. This is very simply accomplished by the setting shown in FIG. l. The thousands slider is set at 5, the hundreds at 3," the tens at 4, and the units at 2. The various products appear in window 14 and are simply added. Thus, in this example, 3.5% of $5,342 is:

The simplicity and usefulness of the device will be apparent.

As a variation of this invention, there is illustrated in FIGS. 4 and 5 a device wherein the various products are printed circularly on concentric discs of different sizes. One advantage of such a construction would be its cheapness, as cardboard or plastic sheet could be employed. The base member 30 carries the digits from zero to nine. In the device illustrated, no thousands disc is shown. The hundreds disc 32, the tens disc 34, and the units disc 36 are suitably marked and rotatably mounted on a central pin 38. In place of the zero on each disc, there is provided an index mark 40 which is set at the proper digit on base 30. The product answers are read at the top of the card. In the illustration, 3.5% of 342 is:

It will be apparent that a number of variations and modifications may be made in this invention without departing from the spirit and scope thereof. This invention is to be construed as limited only by the scope of the following claim.

I claim:

A percentage calculator which comprises: a substantially rectangular body member defining therethrough a plurality of parallel passages, each of rectangular cross section and of substantially equal length; a rst major surface portion of said body member defining therein a plurality of parallel slots, each of said slots communicating with a corresponding passage and extending from a first end of such passage to essentially its mid-point and having a width narrower than its corresponding passage, said surface portion having a first line of equally spaced decimal indicia extending along the length of said slots;

ya plurality of elongated sliding elements, each of rectangular cross section and independently slidably mounted in a different one of said passages, each element having a Width greater than that of its corresponding slot and a length essentially one half the length of said body member, each of said elements carrying a product line of equally spaced decimal indicia representing the product I.of a ixed. percentage, each of the decimal .indiciaof said first line, and a power of ten, the power of ten being different for each of said slider means; indexing handle means mountedV at a; rst end, of each ofsaid slider means and extending through its'corresponding slot for aligning ,each of said slider means relative to a selected indicium `ofzsaid rst line off. indicia; and window means in the unyslotted5portion of saidsurface portion whereby one in- 5V dicium 'of theproduct line of each slider means is exf-pos'ed, `saidiindicium representing the product of (a) said agfixed percentage, (b) saidl selected ,indiciunn and (c) the power of ten of the slider means.

. References ,Cited inihe. flle, Olflthipent UNITED STATES PATENTS Young Sept. 2, 1851 Halsey June 22, 1886 Hill July 6, 1915 Edmondson July 18, 1922 Dalboni l' Ian. 17, 1950 ,FOREIGN PATENTS Austria June 10, 1915 Canada ,Mar` 8, 1,960 

